1. Technical Field
The present disclosure relates to a suspension device for a vehicle, e.g., a motor vehicle.
2. Description of the Related Art
In a vehicle, e.g., a motor vehicle, a plurality of wheels are respectively suspended by corresponding suspensions from a vehicle body. Each of the suspensions includes an elastically deformable member, e.g., a suspension spring, for allowing relative displacement between the wheel and the vehicle body, and a shock absorber for generating a damping force. When a force is input from a road surface to the wheel, this force is transmitted to the vehicle body via the suspension, resulting in excitation of the vehicle body. Thus, an effort is made to decrease the vibration of the vehicle body so as to increase ride comfort of the vehicle by devising a structure of the suspension so that the force input from the road surface to the wheel is prevented from being transmitted to the vehicle body as much as possible.
For example, in Japanese Patent Application Laid-open No. 2009-40349, there is disclosed a suspension configured so that a longitudinal force input from a road surface to a wheel when the wheel vertically strokes is canceled out by a sum of a component in a vehicle longitudinal direction of a force generated by elastic deformation of an elastically deformable member and a component in the vehicle longitudinal direction of a damping force.
In general, a primary function of the suspension is to allow displacement of the wheel in the vertical direction with respect to the vehicle body, and simultaneously attenuate the vibration of the wheel with respect to the vehicle body. Therefore, there is a limit to increasing the magnitude of the component in the vehicle longitudinal direction of the force generated by the elastic deformation of the elastically deformable member and the magnitude of the component in the vehicle longitudinal direction of the damping force without impairing the primary function of the suspension. Thus, there is a limit to decreasing the longitudinal vibration of the vehicle body by devising the structure of the suspension so that the force transmitted to the vehicle body via the suspension is decreased.
Moreover, it is conceivable to set a longitudinal compliance of the suspension to be high in order to decrease the longitudinal force transmitted to the vehicle body via the suspension. However, when the longitudinal compliance of the suspension is set to be high, operation stability of the vehicle decreases, and it is thus difficult to increase both ride comfort of the vehicle and the operation stability of the vehicle.